从手机中选取图片

从手机中选取一张图片然后显示出来。

布局就一个ImageView和一个Button，代码如下：

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context="com.arial.readsdcard.MainActivity" 
    android:orientation="vertical">

    <ImageView 
        android:id="@+id/img"
        android:layout_width="wrap_content"
        android:layout_height="0dp"
        android:layout_weight="1"
        android:scaleType="centerInside"/>
    
    <Button 
        android:id="@+id/btn"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="从手机中选择图片"
        android:layout_gravity="center_horizontal"/>

</LinearLayout>

主代码如下：

public class MainActivity extends Activity {

	ImageView img;
	Button btn;
	Uri uri;
	final int CHOOSE_PHOTO = 1;
	
	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		requestWindowFeature(Window.FEATURE_NO_TITLE);
		setContentView(R.layout.activity_main);
		
		img = (ImageView)findViewById(R.id.img);
		btn = (Button)findViewById(R.id.btn);
		
		btn.setOnClickListener(new OnClickListener() {
			
			@Override
			public void onClick(View arg0) {
				// TODO Auto-generated method stub
				String imageName = System.currentTimeMillis() + ".jpg";
				String imagePath = Environment.getExternalStorageDirectory()
						.getPath() + "/Image/" + imageName;

				File imageFile = new File(imagePath);
				try {
					if (imageFile.exists()) {
//						boolean delete = imageFile.delete();
						imageFile.delete();
					}
					boolean newFile = imageFile.createNewFile();
				} catch (IOException e) {
					e.printStackTrace();
				}

				uri = Uri.fromFile(imageFile);
				Intent intent = new Intent(Intent.ACTION_PICK, null);
				// 调用的是系统图库
				intent.setDataAndType(
						MediaStore.Images.Media.EXTERNAL_CONTENT_URI, "image/*");
				intent.putExtra(MediaStore.EXTRA_OUTPUT, uri);
				startActivityForResult(intent, CHOOSE_PHOTO);
			}
		});
		
	}

	@Override
	protected void onActivityResult(int requestCode, int resultCode, Intent data) {
		// TODO Auto-generated method stub
		if(requestCode == CHOOSE_PHOTO && resultCode == RESULT_OK) {
			try {
				// // 将output_image.jpg对象解析成Bitmap对象，然后设置到ImageView中显示出来
				uri = data.getData();
				Bitmap bitmap = BitmapFactory.decodeStream(getContentResolver()
						.openInputStream(uri));
				img.setImageBitmap(bitmap);

			} catch (FileNotFoundException e) {
				e.printStackTrace();
			}
		}
	}

就酱。